T cells, especially cytotoxic T cells, play important roles in anti-tumor immunity (Rossing and Brenner (2004) Mol. Ther. 10:5-18). Adoptive transfer of tumor-specific T cells into patients provides a means to treat cancer (Sadelain, et al. (2003)Nat. Rev. Cancer 3:35-45). However, the traditional approaches for obtaining large numbers of tumor-specific T cells are time-consuming, laborious and sometimes difficult because the average frequency of antigen-specific T cells in periphery is extremely low (Rosenberg (2001)Nature 411:380-384; Ho, et al. (2003)Cancer Cell 3:431-437; Crowley, et al. (1990) Cancer Res. 50:492-498). In addition, isolation and expansion of T cells that retain their antigen specificity and function can also be a challenging task (Sadelain, et al. (2003) supra). Genetic modification of primary T cells with tumor-specific immunoreceptors, such as full-length T cell receptors or chimeric T cell receptor molecules can be used for redirecting T cells against tumor cells (Stevens, et al. (1995) J. Immunol. 154:762-771; Oelke, et al. (2003) Nat. Med. 9:619-624; Stancovski, et al. (1993) J. Immunol. 151:6577-6582; Clay, et al. (1999) J. Immunol. 163:507-153). This strategy avoids the limitation of low frequency of antigen-specific T cells, allowing for facilitated expansion of tumor-specific T cells to therapeutic doses.
Natural killer (NK) cells are innate effector cells serving as a first line of defense against certain viral infections and tumors (Biron, et al. (1999) Annu. Rev. Immunol. 17:189-220; Trinchieri (1989) Adv. Immunol. 47:187-376). They have also been implicated in the rejection of allogeneic bone marrow transplants (Lanier (1995) Curr. Opin. Immunol. 7:626-631; Yu, et al. (1992) Annu. Rev. Immunol. 10:189-214). Innate effector cells recognize and eliminate their targets with fast kinetics, without prior sensitization. Therefore, NK cells need to sense if cells are transformed, infected, or stressed to discriminate between abnormal and healthy tissues. According to the missing self phenomenon (Kärre, et al. (1986) Nature (London) 319:675-678), NK cells accomplish this by looking for and eliminating cells with aberrant major histocompatibility complex (MHC) class I expression; a concept validated by showing that NK cells are responsible for the rejection of the MHC class I-deficient lymphoma cell line RMA-S, but not its parental MHC class I-positive line RMA.
Inhibitory receptors specific for MHC class I molecules have been identified in mice and humans. The human killer cell Ig-like receptors (KIR) recognize HLA-A, -B, or -C; the murine Ly49 receptors recognize H-2K or H-2D; and the mouse and human CD94/NKG2 receptors are specific for Qa1b or HLA-E, respectively (Long (1999) Annu. Rev. Immunol. 17:875-904; Lanier (1998) Annu. Rev. Immunol. 16:359-393; Vance, et al. (1998) J. Exp. Med. 188:1841-1848).
Activating NK cell receptors specific for classic MHC class I molecules, nonclassic MHC class I molecules or MHC class I-related molecules have been described (Bakker, et al. (2000) Hum. Immunol. 61:18-27). One such receptor is NKG2D (natural killer cell group 2D) which is a C-type lectin-like receptor expressed on NK cells, γδ-TcR+ T cells, and CD8+ αβ-TcR+ T cells (Bauer, et al. (1999) Science 285:727-730). NKG2D is associated with the transmembrane adapter protein DAP10 (Wu, et al. (1999) Science 285:730-732), whose cytoplasmic domain binds to the p85 subunit of the PI-3 kinase.
In humans, two families of ligands for NKG2D have been described (Bahram (2000) Adv. Immunol. 76:1-60; Cerwenka and Lanier (2001) Immunol. Rev. 181:158-169). NKG2D binds to the polymorphic MHC class I chain-related molecules (MIC)-A and MICB (Bauer, et al. (1999) supra). These are expressed on many human tumor cell lines, on several freshly isolated tumor specimens, and at low levels on gut epithelium (Groh, et al. (1999) Proc. Natl. Acad. Sci. USA 96:6879-6884). NKG2D also binds to another family of ligands designated the UL binding proteins (ULBP)-1, -2, and -3 molecules (Cosman, et al. (2001) Immunity 14:123-133; Kubin, et al. (2001) Eur. J. Immunol. 31:1428-1437). Although similar to class I MHC molecules in their α1 and α2 domains, the genes encoding these proteins are not localized within the MHC. Like MIC (Groh, et al. (1996) supra), the ULBP molecules do not associate with β2-microglobulin or bind peptides. The known murine NKG2D-binding repertoire encompasses the retinoic acid early inducible-1 gene products (RAE-1) and the related H60 minor histocompatibility antigen (Cerwenka, et al. (2000) Immunity 12:721-727; Diefenbach, et al. (2000) Nat. Immunol. 1:119-126). RAE-1 and H60 were identified as ligands for mouse NKG2D by expression cloning these cDNA from a mouse transformed lung cell line (Cerwenka, et al. (2000) supra). Transcripts of RAE-1 are rare in adult tissues but abundant in the embryo and on many mouse tumor cell lines, indicating that these are oncofetal antigens.
Recombinant receptors containing an intracellular domain for activating T cells and an extracellular antigen-binding domain, which is typically a single-chain fragment of a monoclonal antibody and is specific for a tumor-specific antigen, are known in the art for targeting tumors for destruction. See, e.g., U.S. Pat. No. 6,410,319.
Baba et al. ((2000) Hum. Immunol. 61:1202-18) teach KIR2DL1-CD3 zeta chain chimeric proteins. Further, WO 02/068615 suggests fusion proteins of NKG2D containing the external domain of NKG2D with a distinct DAP10 interacting domain or with cytoplasmic domains derived from other signaling molecules, for example CD28, for use in engineering cells that respond to NKG2D ligands and potentially create a system with enhanced signaling capabilities.
U.S. Pat. No. 5,359,046 discloses a chimeric DNA sequence encoding a membrane bound protein, wherein the chimeric DNA comprises a DNA sequence encoding a signal sequence which directs the membrane bound protein to the surface membrane; a DNA sequence encoding a non-MHC restricted extracellular binding domain of a surface membrane protein selected from the group consisting of CD4, CD8, IgG and single-chain antibody that binds specifically to at least one ligand, wherein said ligand is a protein on the surface of a cell or a viral protein; a transmembrane domain from a protein selected from the group consisting of CD4, CD8, IgG, single-chain antibody, the CD3 zeta chain, the CD3 gamma chain, the CD3 delta chain and the CD3 epsilon chain; and a cytoplasmic signal-transducing domain of a protein that activates an intracellular messenger system selected from the group consisting of the CD3 zeta chain, the CD3 gamma chain, the CD3 delta chain and the CD3 epsilon chain, wherein the extracellular domain and cytoplasmic domain are not naturally joined together and the cytoplasmic domain is not naturally joined to an extracellular ligand-binding domain, and when the chimeric DNA is expressed as a membrane bound protein in a selected host cell under conditions suitable for expression, the membrane bound protein initiates signaling in the host cell.